The invention relates to a method and an arrangement for designing a technical system.
In order to design a complex technical system it is often necessary to optimize the system with respect to a plurality of contradictory criteria. The criteria influence target functions of the system, such as, for example, manufacturing costs or efficiency. In addition, possible operating points of the system can be restricted by auxiliary conditions. This leads to the problem of determining a set of optimal operating points for the system, that is to say the set of possible operating points of the system with which it is not possible to optimize the operating points further simultaneously with regard to all criteria. From the set of optimal points, individual users can then select the most suitable operating points of the system for their applications while taking into account secret criteria or expert knowledge.
A weighting method for optimizing technical systems with respect to a plurality of criteria is known from C. Hillermeier: “Nonlinear Multiobjective Optimization: A Generalized Homotopy Approach”, Chapter 3.2, Birkhäuser Verlag, 2001 (“the Hillermeier Chapter 3.2 reference”), wherein scaling parameters are employed to apply transformations to scalar-value optimization problems. This method has the disadvantage that it is numerically very involved, because very many scalar-value optimizations have to be performed. Furthermore, the selection and variation of the scaling parameters necessitates an interaction with a user and in this respect cannot be automated.
A stochastic method for optimizing technical systems with respect to a plurality of criteria, wherein a stochastic differential equation is used to solve the optimization problem, is described in C. Hillermeier: “Nonlinear Multiobjective Optimization: A Generalized Homotopy Approach”, Chapter 3.3, Birkhäuser Verlag, 2001. This method has the disadvantage that it are very involved in numerical terms, because a multiplicity of quadratic optimization problems have to be solved. A further disadvantage lies in the fact that with the method, the individual target functions are not weighted, as a result of which important information for selecting an optimal point is not available to the user.
A homotopy method for optimizing technical systems with respect to multiple criteria, wherein in addition to weighting factors for the target functions, Lagrange multipliers are used in order to take auxiliary conditions into account, is known from C. Hillermeier: “A Generalized Homotopy Approach to Multiobjective Optimization”, Journal of Optimization Theory and Application, Vol. 110/3, pp. 557-583, Plenum Press, New York, 2001 (“the Hillemermeier Vol. 110/3 reference”). The disadvantage of this method lies in the fact that an interaction with the user is necessary and in this respect the method cannot be automated.